I've flown to several countries with lots of film. 1) USA TSA are generally receptive to hand checks. 2) most European airports are hit or miss. Heathrow sucks. 3) just be upfront most agents are happy to help. 4) don't sweat it if they do get scanned by the regular hand luggage xray. I had a trip last year were multiple rolls up to 800 took multiple scans. No issues. Just stay away from the new CT scanners.